Irish airline operators had a bad case of déjà-vu this morning when a cloud of ash from the Icelandic volcano Eyjafjallajökull swept over the Emerald Isle and grounded all flights. The Outer Hebrides islands of Scotland were also affected. Flights in the rest of the UK operated normally.

The Irish Aviation Authority canceled all flights in Northern Ireland and the Republic of Ireland starting at 7am local time and allowed them to resume at 1pm local time. The few small airports affected in the Hebrides also plan to reopen sometime in the afternoon.

The ash cloud only reached about 20,000 feet so flights crossing Irish airspace at cruising altitude were not affected. The cloud was thin and sparse compared with the massive one that grounded flights for six days last month. It thinned out to safe levels by the afternoon, prompting aviation officials to reopen service.